Association of Antibiotic Alterations in Gut Microbiota With Decreased Osseointegration of an Intramedullary Nail in Mice With and Without Osteomyelitis.

Xingqi Zhao,Huimin Deng,Zhaohui Zhang,Hanjun Qin,Yiran Wang,Siqi Yang,Haoyang Wan,Nan Jiang,Shihao Wang,Zhengwen Zhu,Bin Yu,Yang Bai,Kai Qian,Yifang Zhang

doi:10.3389/fendo.2021.774257

Abstract

Treatment of osteomyelitis requires prolonged antibiotic therapy which significantly alters the gut microbiota. While the influences on bone mass and microstructure have been extensively studied, it is poorly understood what impact the changes in gut microbiota may have on the host response to osseointegration around an intramedullary nail implanted. Here, we explored the influence of gut microbiota on the bone osseointegration process around an implant under two conditions: implantation of an intramedullary nail in the bone marrow cavity and chronic osteomyelitis (CO) induced by Staphylococcus aureus infection. Body weight, hepatorenal functions, serum levels of proinflammatory cytokines were monitored. The composition of gut microbiota was assessed via 16S rRNA sequencing, and the bone condition was analyzed via micro-computed tomography, hematoxylin and eosin staining, Safranin O-fast green and Goldner’s trichrome staining. Osteoblastogenesis and osteoclastogenesis were assessed by detecting tartrate-resistant acid phosphatase and osterix expression. We found that perturbation of gut microbiota (increase in Proteobacteria and decrease in Bacteroidetes) associated with delayed osseointegration and increased levels of proinflammatory cytokines in the serum (p<0.05), lower bone mass (p<0.05), deficient endochondral ossification and bone formation, reduced osteoblastogenesis (p<0.05) and enhanced osteoclastogenesis (p<0.001). Survival rates (p=0.002) and bacterial loads (p=0.0363) in bone differed significantly between the CO and antibiotic-treated CO mice, but cytokines levels, bone mineral density, and bone formation did not differ, likely because of the severely damaged bone structure. In summary, antibiotic treatment perturbed the gut microbiota and significantly interfered with the bone osseointegration around the nail by increasing proinflammatory cytokine levels in circulation, inhibiting osteoblastogenesis, enhancing osteoclastogenesis, and thus leading to higher pathogen colonization as well as higher mortality postinfection. This report of ours is the first to demonstrate antibiotic-induced alterations in the gut microbiota affect bone osseointegration, helping us understand the role of gut microbiota disorders in osteoblastogenesis and osteoclastogenesis following implant insertion with or without infection.

Highlights

Bacterial infection is a very serious and common complication of implants which are typically used for patients with fractures or severe osteoarthritis in surgery [1]
We explored the role of antibioticinduced perturbation of gut microbiota in osseointegration in response to an intramedullary nail in mice with or without osteomyelitis
Our results demonstrated that perturbing gut microbiota by antibiotics associated with inefficient osseointegration around an intramedullary nail, increased proinflammatory cytokine levels in serum, lower bone mass, deficient bone formation, inhibited osteoblastogenesis and enhanced osteoclastogenesis

Summary

Introduction

Bacterial infection is a very serious and common complication of implants which are typically used for patients with fractures or severe osteoarthritis in surgery [1]. Staphylococcus aureus (S. aureus) is the most common pathogen responsible for such bone infections, which, when uncontrolled, can progress to chronic osteomyelitis (CO), a persistent infection in bone caused by pathogenic microorganisms, often resulting in sequestrum formation and bone destruction [2]. As a persistent and progressive inflammatory disease, CO remains a huge challenge for clinicians and a burden to patients because of its long duration, complex treatment and high relapse rate [3]. Prophylactic antibiotics are commonly prescribed in clinical practice to prevent bone infection. The clinical guidelines for treatment of S. aureusassociated CO generally recommend a combination of antibiotics such as aminoglycosides, gentamicin, and vancomycin [5]

Methods

Results

Conclusion